Sahih Bukhari Volume 6, Book 65, Hadith 4818

حَدَّثَنَا الصَّلْتُ بْنُ مُحَمَّدٍ، حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، عَنْ رَوْحِ بْنِ الْقَاسِمِ، عَنْ مَنْصُورٍ، عَنْ مُجَاهِدٍ، عَنْ أَبِي مَعْمَرٍ، عَنِ ابْنِ مَسْعُودٍ، ‏{‏وَمَا كُنْتُمْ تَسْتَتِرُونَ أَنْ يَشْهَدَ، عَلَيْكُمْ سَمْعُكُمْ‏}‏ الآيَةَ كَانَ رَجُلاَنِ مِنْ قُرَيْشٍ وَخَتَنٌ لَهُمَا مِنْ ثَقِيفَ، أَوْ رَجُلاَنِ مِنْ ثَقِيفَ وَخَتَنٌ لَهُمَا مِنْ قُرَيْشٍ فِي بَيْتٍ فَقَالَ بَعْضُهُمْ لِبَعْضٍ أَتُرَوْنَ أَنَّ اللَّهَ يَسْمَعُ حَدِيثَنَا قَالَ بَعْضُهُمْ يَسْمَعُ بَعْضَهُ‏.‏ وَقَالَ بَعْضُهُمْ لَئِنْ كَانَ يَسْمَعُ بَعْضَهُ لَقَدْ يَسْمَعُ كُلَّهُ‏.‏ فَأُنْزِلَتْ ‏{‏وَمَا كُنْتُمْ تَسْتَتِرُونَ أَنْ يَشْهَدَ عَلَيْكُمْ سَمْعُكُمْ وَلاَ أَبْصَارُكُمْ‏}‏ الآيَةَ ‏{‏وَذَلِكُمْ ظَنُّكُمُ‏}‏ الآيَةَ‏.‏

Narrated By Ibn Mas'ud : (Regarding) the Verse: 'And you have not been screening against yourself lest your ears, and your eyes and your skins should testify against you...' (41.22) While two persons from Quraish and their brother-in-law from Thaqif (or two persons from Thaqif and their brother-in-law from Quraish) were in a house, they said to each other, "Do you think that Allah hears our talks?" Some said, "He hears a portion thereof" Others said, "If He can hear a portion of it, He can hear all of it." Then the following Verse was revealed: 'And you have not been screening against yourself lest your ears, and your eyes and your skins should testify against you...' (41.22)